Implement in-process multi-dataset sync isolation across core, network, persistence, and tests

tests/ZB.MOM.WW.CBDDC.Network.Tests/ProtocolTests.cs

@@ -1,4 +1,6 @@
 using Microsoft.Extensions.Logging.Abstractions;
+using Google.Protobuf;
+using ZB.MOM.WW.CBDDC.Core;
 using ZB.MOM.WW.CBDDC.Network.Proto;
 using ZB.MOM.WW.CBDDC.Network.Protocol;
 using ZB.MOM.WW.CBDDC.Network.Security;
@@ -145,6 +147,44 @@ public class ProtocolTests
         decoded.NodeId.ShouldBe("fragmented");
     }
 
+    /// <summary>
+    ///     Verifies that dataset-aware protocol fields are serialized and parsed correctly.
+    /// </summary>
+    [Fact]
+    public void DatasetAwareMessages_ShouldRoundTripDatasetFields()
+    {
+        var request = new PullChangesRequest
+        {
+            SinceWall = 10,
+            SinceLogic = 1,
+            SinceNode = "node-a",
+            DatasetId = "logs"
+        };
+
+        byte[] payload = request.ToByteArray();
+        var decoded = PullChangesRequest.Parser.ParseFrom(payload);
+
+        decoded.DatasetId.ShouldBe("logs");
+    }
+
+    /// <summary>
+    ///     Verifies that legacy messages with no dataset id default to the primary dataset.
+    /// </summary>
+    [Fact]
+    public void DatasetAwareMessages_WhenMissingDataset_ShouldDefaultToPrimary()
+    {
+        var legacy = new HandshakeRequest
+        {
+            NodeId = "node-legacy",
+            AuthToken = "token"
+        };
+
+        byte[] payload = legacy.ToByteArray();
+        var decoded = HandshakeRequest.Parser.ParseFrom(payload);
+
+        DatasetId.Normalize(decoded.DatasetId).ShouldBe(DatasetId.Primary);
+    }
+
     // Helper Stream for fragmentation test
     private class FragmentedMemoryStream : MemoryStream
     {
@@ -169,4 +209,4 @@ public class ProtocolTests
             return await base.ReadAsync(buffer, offset, toRead, cancellationToken);
         }
     }
-}
+}